The invention relates to the activation of hepatitis C virus(HCV)-specific T cells. More particularly, the invention relates to the use of multiple HCV polypeptides, either alone or as fusions, to stimulate cell-mediated immune responses, such as to activate HCV-specific T cells.
Hepatitis C virus (HCV) infection is an important health problem with approximately 1% of the world""s population infected with the virus. Over 75% of acutely infected individuals eventually progress to a chronic carrier state that can result in cirrhosis, liver failure, and hepatocellular carcinoma. See Alter et al. (1992) N. Engl. J. Med. 327:1899-1905; Resnick and Koff. (1993) Arch. Intem. Med. 153:1672-1677; Seeff (1995) Gastrointest. Dis. 6:20-27; Tong et al. (1995) N. Engl. J. Med. 332:1463-1466.
Despite extensive advances in the development of pharmaceuticals against certain viruses like HIV, control of acute and chronic HCV infection has had limited success (Hooffiagle and di Bisceglie (1997) N. Engl. J. Med. 336:347-356). In particular, generation of a strong cytotoxic T lymphocyte (CTL) response is thought to be important for the control and eradication of HCV infections. Thus, there is a need in the art for effective methods of inducing strong CTL responses against HCV.
It is an object of the invention to provide reagents and methods for activating T cells which recognize epitopes of HCV polypeptides. This and other objects of the invention are provided by one or more of the embodiments described below.
The invention provides HCV proteins useful for activating HCV-specific T cells. One embodiment provides a fusion protein that consists essentially of an NS3, an NS4, and an NS5a polypeptide.
Another embodiment provides a fusion protein that consists essentially of an NS3, an NS4, an NS5a, and NS5b polypeptide of an HCV.
Still another embodiment of the invention provides a fusion protein comprising an NS3, an NS4, an NS5a and optionally an NS5b polypeptide of an HCV. One of the HCV polypeptides is derived from a different strain of HCV than the other polypeptides.
The invention also provides compositions comprising any of these fusion proteins and a pharmaceutically acceptable carrier.
Another embodiment provides a composition consisting essentially of an NS3, an NS4, and an NS5a polypeptide, or a composition consisting essentially of polynucleotides encoding the individual proteins.
Another embodiment provides a composition that consists essentially of an NS3, an NS4, an NS5a, and NS5b polypeptide of an HCV, or a composition consisting essentially of polynucleotides encoding the individual proteins.
Still another embodiment of the invention provides a composition consisting essentially of an NS3, an NS4, an NS5a and optionally an NS5b polypeptide of an HCV, or a composition consisting essentially of polynucleotides encoding the individual proteins. One of the HCV polypeptides or polynucleotides is derived from a different strain of HCV than the others.
Even another embodiment of the invention provides an isolated and purified polynucleotide which encodes a fusion protein consisting essentially of an NS3, an NS4, and an NS5a polypeptide of an HCV or a fusion protein consisting essentially of an NS3, an NS4, an NS5a, and an NS5b polypeptide of an HCV.
Yet another embodiment of the invention provides a composition comprising an isolated and purified polynucleotide which encodes a fusion protein consisting essentially of either an NS3, an NS4, and an NS5a polypeptide of an HCV or consisting essentially of an NS3, an NS4, an NS5a, and an NS5b polypeptide of an HCV. The composition also comprises a pharmaceutically acceptable carrier.
Another embodiment of the invention provides isolated and purified polynucleotide which encodes a fusion protein comprising an NS3, an NS4, and an NS5a polypeptide of an HCV in which one of the NS3, NS4, and NS5a polypeptides is derived from a different strain of HCV than the other two polypeptides. The invention also provides a composition comprising this polynucleotide and a pharmaceutically acceptable carrier.
Yet another embodiment of the invention provides an isolated and purified polynucleotide which encodes a fusion protein comprising an NS3, an NS4, an NS5a, and an NS5b polypeptide of an HCV. One of the polypeptides is derived from a different strain of HCV than the other polypeptides. The invention also provides a composition comprising this polynucleotide and a pharmaceutically acceptable carrier.
Even another embodiment of the invention provides a method of activating T cells which recognize an epitope of an HCV polypeptide. T cells are contacted with a fusion protein comprising an NS3, an NS4, and an NS5a polypeptide of an HCV. A population of activated T cells recognizes an epitope of the NS3, NS4, or NS5a polypeptide. Alternatively, T cells are contacted with a fusion protein comprising an HCV NS3, NS4, NS5a, NS5b polypeptide of an HCV. A population of activated T cells recognizes an epitope of the NS3, NS4, NS5a, or NS5b polypeptide.
The invention thus provides methods and reagents for activating T cells which recognize epitopes of HCV polypeptides. These methods and reagents are particularly advantageous for identifying epitopes of HCV polypeptides associated with a strong CTL response and for immunizing mammals, including humans, against HCV.